CS485/540 Software Engineering Architecture and Component Design (Chs. 9,10)

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1 CS485/540 Software Engineering Architecture and Component Design (Chs. 9,10) Cengiz Günay Dept. Math & CS, Emory University Fall 2013 Some slides courtesy of Joan Smith, Roger Pressman, Ian Sommerville, and the Internets Günay (Emory) Architecture, Component Design Fall / 7

2 Class #16 Scrum: #9 Due today: Iteration plans User stories and subtasks Assigned to who; are you ready? Timeline: Demo date and audience Günay (Emory) Architecture, Component Design Fall / 7

3 Class #16 Scrum: #9 Due today: Iteration plans User stories and subtasks Assigned to who; are you ready? Timeline: Demo date and audience Due Next Thursday: Preliminary proposals of... Architecture design: including directories Lead developer: Coding standards Test plan: acceptance, integration & unit testing framework Data design: database, data file formats, internal data structures Documentation standards: user, code Günay (Emory) Architecture, Component Design Fall / 7

4 Class #16 Scrum: #9 Due today: Iteration plans User stories and subtasks Assigned to who; are you ready? Timeline: Demo date and audience Due Next Thursday: Preliminary proposals of... Today: Architecture design: including directories Lead developer: Coding standards Test plan: acceptance, integration & unit testing framework Data design: database, data file formats, internal data structures Documentation standards: user, code Chris reading. Architecture, Component-level, and User Interface Design (Chs. 9, 10, 11) Günay (Emory) Architecture, Component Design Fall / 7

7 Why is Architecture Important?!! Representations of software architecture are an enabler for communication between all parties (stakeholders) interested in the development of a computer-based system.!! The architecture highlights early design decisions that will have a profound impact on all software engineering work that follows and, as important, on the ultimate success of the system as an operational entity.!! Architecture constitutes a relatively small, intellectually graspable mode of how the system is structured and how its components work together [BAS03].! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 3!

8 (c) vintageprintable.com

9 Architectural Styles!! Data-centered architectures!! Data flow architectures!! Call and return architectures!! Object-oriented architectures!! Layered architectures! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 6!

Layered Architecture! (McGraw-Hill, 2009).

14 Architectural Patterns!! Concurrency applications must handle multiple tasks in a manner that simulates parallelism!! operating system process management pattern!! task scheduler pattern!! Persistence Data persists if it survives past the execution of the process that created it. Two patterns are common:!! a database management system pattern that applies the storage and retrieval capability of a DBMS to the application architecture!! an application level persistence pattern that builds persistence features into the application architecture!! Distribution the manner in which systems or components within systems communicate with one another in a distributed environment!! A broker acts as a ʻmiddle-manʼ between the client component and a server component.! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 11!

21 Component Structure! SafeHome Executive Function selection External Communication Management Security Surveillance Home management GUI Internet Interface Control panel processing detector management alarm processing (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 15!

22 Refined Component Structure! SafeHome Executive External Communication Management Security GUI Internet Interface Control panel processing detector management alarm processing Keypad processing scheduler phone communication CP display functions alarm (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 16! sensor sensor sensor sensor sensor sensor

23 Horizontal Partitioning! define separate branches of the module hierarchy for each major function! use control modules to coordinate communication between functions! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 23!

24 Vertical Partitioning: Factoring! design so that decision making and work are stratified! decision making modules should reside at the top of the architecture! decision-makers workers (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 24!

25 Structured Design! objective: to derive a program architecture that is partitioned! approach:! a DFD is mapped into a program architecture! the PSPEC and STD are used to indicate the content of each module! notation: structure chart! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 26!

27 Architectural Complexity! the overall complexity of a proposed architecture is assessed by considering the dependencies between components within the architecture [Zha98]! Sharing dependencies represent dependence relationships among consumers who use the same resource or producers who produce for the same consumers.! Flow dependencies represent dependence relationships between producers and consumers of resources.! Constrained dependencies represent constraints on the relative flow of control among a set of activities.! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 18!

28 ADL!! Architectural description language (ADL) provides a semantics and syntax for describing a software architecture!! Provide the designer with the ability to:!! decompose architectural components!! compose individual components into larger architectural blocks and!! represent interfaces (connection mechanisms) between components.! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 19!

29 Architecture Description Language (ADL) is Dead? Stanford Rapide: Exectuable ADL ( ) Used for Complex event processing (CEP) ( ) UniCon from CMU (obsolete) Aesop from CMU (research ) Wright from CMU ABLE Lab (research ) So anybody alive? Wikipedia page What Industry Needs from Architectural Languages: A Survey (2013) UML (still active!) Günay (Emory) Architecture, Component Design Fall / 7

30 Other Architectural Issues Open Source Development: Choosing a license affects architecture? Platform independence Host-target system problems Günay (Emory) Architecture, Component Design Fall / 7

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32 Chapter 10!! Component-Level Design! Slide Set to accompany Software Engineering: A Practitionerʼs Approach, 7/e # by Roger S. Pressman Slides copyright 1996, 2001, 2005, 2009 by Roger S. Pressman For non-profit educational use only May be reproduced ONLY for student use at the university level when used in conjunction with Software Engineering: A Practitioner's Approach, 7/e. Any other reproduction or use is prohibited without the express written permission of the author. All copyright information MUST appear if these slides are posted on a website for student use. (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 1!

33 computepagecost() computepapercost() computeprodcost() computetotaljobcost() buildworkorder() checkpriority () passjobto Production() numberofpages numberofsides papertype paperweight papersize papercolor magnification colorrequirements productionfeatures collationoptions bindingoptions coverstock bleed priority totaljobcost WOnumber computepagecost () computepapercost() computeprodcost() computetotaljobcost () buildworkorder() checkpriority () passjobto Production() OO Component! analysis class PrintJob numberofpages numberofsides papertype magnification productionfeatur es computejobcost() passjobtoprinter() computejob design component PrintJob initiatejob <<interface>> computejob <<interface>> initiatejob elaborated design class PrintJob (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 3!

34 Conventional Component! getjobdata design component ComputePageCost accesscostsdb elaborated module PageCost in: numberpages in: numberdocs in: sides= 1, 2 in: color=1, 2, 3, 4 in: page size = A, B, C, B out: page cost in: job size in: color=1, 2, 3, 4 in: pagesize = A, B, C, B out: BPC out: SF getjobdata (numberpages, numberdocs, sides, color, pagesize, pagecost) accesscostsdb(jobsize, color, pagesize, BPC, SF) computepagecost() job size (JS) = numberpages * numberdocs; lookup base page cost (BPC) --> accesscostsdb (JS, color); lookup size factor (SF) --> accesscostdb (JS, color, size) job complexity factor (JCF) = 1 + [(sides-1)*sidecost + SF] pagecost = BPC * JCF (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 4!

35 Basic Design Principles!! The Open-Closed Principle (OCP). A module [component] should be open for extension but closed for modification."! The Liskov Substitution Principle (LSP). Subclasses should be substitutable for their base classes."! Dependency Inversion Principle (DIP). Depend on abstractions. Do not depend on concretions.!! The Interface Segregation Principle (ISP). Many client-specific interfaces are better than one general purpose interface."! The Release Reuse Equivalency Principle (REP). The granule of reuse is the granule of release.!! The Common Closure Principle (CCP). Classes that change together belong together. "! The Common Reuse Principle (CRP). Classes that arenʼt reused together should not be grouped together.! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 5!

36 Design Guidelines!! Components!! Naming conventions should be established for components that are specified as part of the architectural model and then refined and elaborated as part of the component-level model!! Interfaces!! Interfaces provide important information about communication and collaboration (as well as helping us to achieve the OPC)!! Dependencies and Inheritance!! it is a good idea to model dependencies from left to right and inheritance from bottom (derived classes) to top (base classes).! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 6!

37 Cohesion!! Conventional view:!! the single-mindedness of a module!! OO view:!! cohesion implies that a component or class encapsulates only attributes and operations that are closely related to one another and to the class or component itself!! Levels of cohesion!! Functional!! Layer!! Communicational!! Sequential!! Procedural!! Temporal!! utility! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 7!

38 Coupling!! Conventional view:!! The degree to which a component is connected to other components and to the external world!! OO view:!! a qualitative measure of the degree to which classes are connected to one another!! Level of coupling!! Content!! Common!! Control!! Stamp!! Data!! Routine call!! Type use!! Inclusion or import!! External! (McGraw-Hill, 2009). Slides copyright 2009 by Roger Pressman.! 8!

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!#$%&'()*+,-*,--)./00#'1)2)345645%() !"#$%&'()*+,-*,--)./00#'1)2)345"645"%() Chapter 9!! Architectural Design! Slide Set to accompany Software Engineering: A Practitionerʼs Approach, 7/e # by Roger S. Pressman Slides copyright 1996, 2001,